Gypsum is added to cement clinker to

Option A: Increase the tensile strength of cement:
This statement is incorrect. Gypsum is not added to cement clinker to increase its tensile strength. Tensile strength is the ability of a material to withstand pulling or stretching forces.

Option B: Decrease the rate of setting of cement:
This statement is correct. Gypsum is added to cement clinker to control the setting time of cement. It acts as a retarder, slowing down the rate at which the cement mixture hardens. This is important for allowing enough time for proper mixing, placing, and finishing of the cement before it sets.

Option C: Facilitate the formation of colloidal gel:
This statement is incorrect. Gypsum does not facilitate the formation of a colloidal gel. Colloidal gels are formed through different processes and materials.

Option D: Bind the particles of calcium silicate:
This statement is incorrect. Gypsum is not added to bind the particles of calcium silicate. The main component of cement clinker is calcium silicate, and gypsum is added for a different purpose, as explained in Option B.

In summary, gypsum is added to cement clinker to decrease the rate of setting, which allows for better handling and working of the cement mixture before it hardens. This ensures that the cement can be properly placed and finished in construction applications.